The broad objective of this Mass Spectrometry Core is to provide high- end mass spectroscopy techniques to support the biomedical and non- biomedical projects in this Superfund Basic Research Program and to develop and apply a new, highly specific and sensitive mass spectroscopy technique to detect and quantify environmental compounds and their metabolites. These compounds will include tetrachloroethene, 1,1,2- trichloroethene, cis-1,2-dichloroethene, vinyl chloride, chloroacetaldehyde and chloroform. The development of this new instrument will require the construction of a gas chromatograph electron monochromater-time-of flight-mass spectrometer (GC-EM-TOF-MS) to analyze negative ions using the EM for the production of monoenergetic beams of ionizing electrons in combination with pulsed extraction. To support the other biomedical and non-biomedical projects in this application, we will develop and apply mass spectrometric methods to analyze adducts formed between proteins and hydrocarbon solvent metabolites. We will develop mass spectrometric methods for analyzing protein and peptides resulting from reaction with 2,5-hexanedione, and analogs, 3-methyl-2,5-hexanedione, 3,4-dimethyl-2,5-hexanedione, 3-4- diethyl-2,5-hexanedione, 2,9-dimethyl-4,7, decanedione and 1,2- diacetylbenzene. The effects of gamma-diketone hydrocarbon adducts on the thermal stability of neurofilament protein structures will be a assessed by hydrogen-deuterium exchange (H/D) exchange and equilibrium thermal denaturation studies in conjunction with electrospray mass spectroscopy. The effects of hydrocarbon adducts on the conformation of neurofilament protein subunits will be determined by kinetic H/D exchange experiments, together with electrospray mas spectrometry.